The invention generally relates to a known type of heat protection casing such as that known from the German journal: Feingeratetechnik Vol. 9, 4 (1960), pages 148-153. A chimney effect and thus good heat removal due to convection is achieved by means of holes close to the cover and base plate of the heat protection casing and by means of an intermediate flow duct which is as long as possible. Vertical chassis arrangements and large cooling surfaces bring further improvements in the cooling effect. It was possible to reduce the temperatures in the interior of the heat protection casing by half by means of surfaces having good radiation characteristics. According to this printed document, metallic surfaces which are bare on one side or even both sides must be rejected if they are to remove heat.